Susumu egawa

ABSTRACT

A DYNAMIC CONVERGENCE DEVICE FOR A THREE-ELECTRON-GUN COLOR TELEVISION RECEIVER, WHICH IS MINIATURIZED AND MANUFACTURED AT LOW COST AS COMPARED WITH THE CONVENTIONAL DEVICES OF THIS TYPE. IN THE DYNAMIC CONVERGENCE DEVICE DISCLOSED HEREIN, A PAIR OF CONVERGENCE ASSEMBLIES EACH COMPRISING A CORE AND A COIL ARE POSITIONED SYMMETRICALLY WITH RESPECT TO THE LONGITUDINAL AXIS OF A PICTURE TUBE, ONE OF THE CONVERGENCE ASSEMBLIES BEING ASSOCIATED WITH ONE OF THE POLE PIECES FOR SAID PICTURE TUBE AND THE OTHER CONVERGENCE ASSEMBLY BEING ASSOCIATED WITH THE REMAINING   TWO POLE PIECES, AND CURRENTS OF PARABOLIC WAVEFORM FLOW THROUGH SAID COILS.

Re. 27,417 ERGENCE DEVICE FOR THREE ELECTRON GUN COLOR TELEVISION RECEIVER Original Filed Dec. 11, 1967 SUSUMU EGAWA July 4, 1972 v DYNAMIC CONV 3 Sheets-Sheet 1 INVENTOR I .rusunu 569w? ATTORNEYS Re.'27,4,l7

July 4, 1972 'susuMu EGAWA DYNAMIC- CONVERGENCE DEVICE FOR THREE ELECTRQN GUN COLOR TELEVISION RECEIVER Original Filed Dec. 11, 1967 3 Sheets-Sheet 2 INVENTOR .cusunu. Q $69M? (M4 /flam ATTORNEYS y 4, 1972 susUMu EGAWA Re. 27,417

DYNAMIC CONVERGENCE DEVICEFOR THREE ELECTRON GUN COLOR TELEVISION RECEIVER Orlgi'nai Filed Dec. 11, 1967 3 Sheets-Sheet 5 INVENTOR I .rumnu 56mm ATTOR NEYS United States Patent 27,417 DYNAMIC CONVERGENCE DEVICE FOR THREE ELECTRON GUN COLOR TELEVISION RECEIVER Susumu Egawa, Osaka, Japan, assignor to Matsushita Electric Industrial Co., Ltd., Osaka, Japan Original No. 3,461,341, dated Aug. 12, 1969, Ser. No.

689,551, Dec. 11, 1967. Application for reissue May 26, 1970, Ser. No. 40,748

Int. Cl. H015 29/50, 29/70 US. Cl. 315-13 C 7 Claims Matter enclosed in heavy brackets appears in the original patent but forms no part of this reissue specification; matter printed in italics indicates the additions made by reissue.

ABSTRACT OF THE DISCLOSURE A dynamic convergence device for a three-electron-gun color television receiver, which is miniaturized and manufactured at low cost as compared with the conventional devices of this type. In the dynamic convergence device disclosed herein, a pair of convergence assemblies each comprising a core and a coil are positioned symmetrically with respect to the longitudinal axis of a picture tube, one of the convergence assemblies being associated with one of the pole pieces for said picture tube and the other convergence assembly being associated with the remaining two pole pieces, and currents of parabolic waveform flow through said coils.

This invention relates to color television, and more particularly it pertains to a dynamic convergence device for a color television receiver.

It is a primary object of the present invention to porvide a simplified dynamic convergence system for color television.

Another object of the present invention is to simplify the convergence yoke assembly associated with the threeelectron-gun color picture tube which is commonly used at present, thereby providing such convergence system which is simplified in construction, manufactured at low cost and easily adjusted.

Other objects, features and advantages of this invention will become apparent from the following description taken in conjunction with the accompanying drawings, in which:

FIG. 1 is a schematic view showing a conventional convergence device for a color television receiver;

FIG. 2 is a view useful for explaining the color-misconvergence and at the same time determining the directions of the currents flowing through the coils;

FIG. 3 is a schematic view showing the dynamic convergence device for a color television receiver according to an embodiment of this invention;

FIGS. 42. and 4b are views showing examples of the main portion of the device shown in FIG. 3;

FIG. 5 shows an example of the convergence circuit according to this invention; and

FIG. 6 shows another example of the convergence device according to this invention.

FIGS. 7a, 7b and 7c are views useful for explaining the operation of the device as shown in FIG. 6.

Referring to FIG. 1, there is shown the conventional convergence device, wherein three magnet means 2 are positioned around the neck portion 1 of a picture tube including three electron-guns R, G and B. Static convergence and blue lateral adjustments are effected with re spect to the respective primary colors while looking at the center portion of the screen, and thereafter dynamic convergence adjustment is effected by flowing a current of parabolic waveform through each dynamic convergence coil 3. This dynamic convergence adjustment is intended ICE to superimpose the three primary colors upon each other mainly in the peripheral portion of the screen. Misconvergence depends upon the curvatures of the focal plane of each primary color and front plane, and it is approximately corrected with respect to its amount in accordance to the square of the distance from the center of the screen. Thus, parabolic currents at field and line frequency are caused to fiow through the coils 3, thereby effecting approximate superposition of the three primary colors in the peripheral portion of the screen. The displacement of beam-dots due to the dynamic convergence is in the radial direction, as can be seen from the drawing. For the convenience of explanation, the positive directions of the respective primary colors R, G and B are determined as indicated in FIG. 2. (In this figure, R, G and B represents the relationship in position between the three color-dots as these color dots are subjected to misconvergence when no dynamic convergence is applied.) Furthermore, a current causing a displacement of each color-dot in the positive direction is referred to as current in the positive direction hereinafter. The adjustment procedure will now be described by way of example. First, a vertical adjustment is performed as follows:

(i) A parabolic current of a suitable amplitude (referred to as AMP component) is caused to fiow through each of the red and green coils in order to accurately align the red and green dots in the vertical direction as viewed on a vertical line passing through the center of the screen. In this case, if there is a difference between the amount of correction to be made in the upper portion of the screen and that to be made in the lower portion of the screen, a current of saw-tooth waveform will be required, which is called TILT component. Such sawtooth wave current of suitable amplitude can be formed by applying a pulse voltage to each coil.

(ii) A blue image is superposed upon a yellow image resulting from the alignment of the red and green images effected in the above manner. In this case, too, AMP and TILT components will be required for the same reason as described above.

(iii) The horizontal adjustment is also effected in the order of RG and B by substantially the same procedure.

In view of the fact that there is a considerable similarity between red and green in respect of the necessary amount of dynamic convergence correction and waveform, the present invention intends to drive red and green beams by the use of the opposite legs of a single common core provided for the red and green electron guns, thereby producing substantially the same effect as in the prior art.

This invention will now be described in greater detail with reference to the drawings. FIG. 3 is a view showing the neck portion of a picture tube taken in section in the vicinity of the screen of the picture tube, as viewed toward the electron guns. A Y-shaped shielding plate 5 is provided in the neck portion 4. In the portion surrounded by the tube wall of the neck portion 4 and the shielding plate 5 are provided pole pieces 6, 6, 6" each formed by a pair of bent metal sheet electrodes disposed in opposing relationship with each other, respectively. Electron guns 7, 7', 7" are provided in the end portions of the neck portion 4 in such a manner that each of the electron beams therefrom is caused to pass through between the 7 pair of electrodes of each of the pole pieces 6, 6', 6". The

reference numeral 7 represents the blue electron gun, 7' the green electron gun, and 7" the red electron gun. The above arrangement is the same as that of the conventional picture tube. In accordance with this invention, a U-shaped core 8 is provided in such a manner that the opposite legs thereof are disposed in opposing relationship with the two electrodes forming the pole piece 6 associated with the blue electron gun 7. Coils 3 are wound on the legs of the core 8. Also, another l-shaped core 10 is provided in such a manner that the pposite legs thereof are disposed in opposing relationship rith the adjacent ones of the electrodes constituting the ole pieces 6 and 6" associated with the green and red electron guns 7' and 7. AMP coils 11, preferbly as shown in FIG. 3, and a differential coil 12 are round on the legs of the core 10. The AMP coils are eparately wound on the respective legs of the core 10 nd connected in series with each other, while the diferential coil is wound in such a manner as to surround oth legs of the core 10 so that the polarities of magnetizaion of the legs by a current flowing through the diferential coil are the same. In FIG. 3, there are shown tatic convergence magnets 13- and 14, iron pieces 15 nd 16 for producing a radial magnetic field, and the like. These elements constitute a novel dipole static conergence device. But they have no direct relation with he present invention, and therefore description thereof rill be omitted.

Description will now be made of the operation of the evice according to this invention.The coils 9 wound on he opposite legs of the core 8 are connected in series vith each other, and a parabolic current is caused to flow hrough each of the coils, so that correction in the upper .nd lower portions of the screen is effected.

Since the red electron gun 7" and the green elecron gun 7 are arranged in the same horizontal plane, the red and green beam spots prior to being subjected dynamic convergence are horizontally spaced apart rom each other, as shown in FIG. 2. By flowing a paraolic current through the AMP coil 11 as shown in T6. 4a, it is possible to bring these beam spots almost uto [approximate] register with each other. [The] If my vertical misconvergence [occurring] still occurs ven after the [correction] adjustment just described jean], such misconvergence may be corrected by flowing parabolic current through the differential coil 12 so hat both legs of the core having the coil 12 wound hereon are magnetized in the same polarity [so as to orrect] as previously described thereby to adjust the red beam in the negative direction and the green Ieam in the positive direction, as shown in FIG. 4b.

The present device may be incorporated in the horizonal convergence circuit, as shown in FIG. 5. In FIG. 5, he reference numeral 17 represents a fly-back pulse input erminal connected with a secondary winding of a horizonal output transformer coupled to a horizontal output ube. The input terminal 17 is connected with one end of he convergence coil 9 (see FIG. 3) through a series cir- :uit consisting of a capacitor 18 and a blue rightward idjustment coil 19. The other end of the coil 9 is grounded. A series circuit consisting of a resistor 20 and liode 21 and a series circuit consisting of a capacitor 22 ind variable resistor 23 are inserted between the connecion point between the coils 9 and 19 and the ground.

The input terminal 17 is also connected with one end )f the AMP coil 11 (see FIG. 3) through a series cir- :uit of a capacitor 24 and a red and green rightward idjustment coil 25. The other end of the coil 11 is grounded. Between the connection point between the 'AMP coil 11 and the adjustment coil 25 and the ground ire inserted a series circuit consisting of a resistor 26 and liode 27 and a series circuit consisting of a capacitor 28 md a variable resistor 29. A variable resistor 30 has its ixed terminals connected with the opposite ends of the AMP coil 11 and its movable terminal connected with he connection point between the two coil sections con- .tituting the AMP coil 11. The adjustment coil 19 orms a transformer of which the secondary winding 31 ias its opposite ends connected with the fixed contacts of l change-over switch 32. The movable contact of the :witch 32 is connected with one end of the differential :oil 12 (see FIG. 3) through a variable resistor 33. The

other end of the coil 12 is grounded. Fly-back pulses applied to the input terminal 17 are integrated so that a parabolic current flows through the yoke coils 9 and 11, as shown in FIG. 5. Thus, the horizontal correction is effected. In this case, pulses are induced in the secondary winding 31 associated with the adjustment coil 19, as shown in FIG. 5. Such induced pulses are applied to the different coil 12 so that a saw-tooth wave current flows therethrough to effect correction. By changing the polarity of the pulses applied to the differential coil 12 by means of the switch 32, the magnetization of the core 10 shown in FIG. 4b is reversed, whereby the direction of correction can be reversed. Such correction can also be effected by moving the movable terminal of the variable resistor 30.

The core 10 is formed with a gap 10 in its center portion. This gap 10' serves to increase the differential component in the differential adjustment by the variable resistor 30. That is, in the case of an integral core, there is a tendency that the intensities of magnetization in the opposite legs thereof assume an averag, value if there is a difference in ampere-turn between the left and right coil sections of the coil wound on such integral core. By forming the gap in the center portion of the core 10, the coupling between the twocoil sections of the coil 11 can be weakened so that the differential component can be increased.

Description will now be made of the vertical convergence device with reference to FIG. 6. A vertical output tube 34 has the plate thereof connected with a primary winding 36 of a vertical output transformer 35 and the cathode thereof grounded through a resistor 37. The cathode is also connected with a variable resistor 40 through a parallel circuit consisting of a capacitor 38 and resistor 39. The other end of the variable resistor 40 is grounded through a variable resistor 41.

The secondary winding 42 of the vertical output tran former 35 is connected with a deflecting circuit (not shown), and a third winding 43 is connected with the opposite fixed terminals of a variable resistor 46 through a parallel circuit of a resistor 44 and capacitor 45. A variable resistor 47 is connected in parallel with the variable resistor 46, and the intermediate terminals of the variable resistors 46 and 47 are grounded, The movable terminal of the variable resistor 46 is connected with the movable terminal of the variable resistor 41 through a convergence coil 9'. The movable terminal of the variable resistor 47 is connected with the movable terminal of the variable resistor 40 through an AMP coil 11.

The opposite ends of a fourth winding 48 of the vertical output transformer 35 are connected with the opposite terminals of a variable resistor 51 through a parallel circuit of a resistor 49 and capacitor 50, and the intermediate terminal of the variable resistor 51 is connected directly with the connection point between the two coil sections forming the AMP coil 11'. The movable terminal of the variable resistor 51 is connected with the movable terminal of a variable resistor 52 connected in parallel with the AMP coil 11'.

From the third winding of the vertical output transformer 35 are taken out such pulses with an oblique portion as shown in the drawing, which are in turn supplied to the parallel circuit of the resistor 44 and capacitor 45 so that they have their oblique portions removed so as to be converted to linear pulses. Such linear pulses are applied to the coil 11' so that a saw-tooth wave current flows therethrough. At the cathode of the vertical output tube is produced such a voltage as shown in the drawing, which is in turn applied to the parallel circuit consisting of the capacitor 38 and resistor 39 to control the DC. component so that the dynamic convergence current with respect to the center portion of the picture tube becomes zero. The voltage is then applied to the yoke coil to cause a parabolic current to flow therethrough. Thus, the vertical correction can be effected.

In this vertical convergence device, no difierential coil is provided, but the same function is achieved by means of the variable resistors 51 and 52. The operation will now be described. In case the red and green beam spots R and G are scattered as shown in FIG. 7a, the correction therefor is effected by means of the variable resistor 52. That is, the variable resistor 52 is adjusted so that the current flowing through one of the two coil sections forming the coil 11 is increased while the current flowing through the other co-il section is decreased, thus bringing the beam spots R and G into register with each other.

If there occurs such misconvergence as shown in FIG. 7b, it can be corrected by flowing a saw-tooth wave current of opposite polarity through the two coil sections of the coil 11', as shown in FIG. 7c. To this end, a pulse voltage is taken out of the Winding 48, and its amount and polarity is controlled by means of the variable resistor 51.

What is claimed is:

1. A dynamic convergence device for a color television receiver having a triple-gun color picture tube provided with three pole pieces positioned inside the neck portion of said color picture tube symmetrically to one another [and] with respect to the axis of said color picture tube, comprising: a first U-shaped core provided outside said neck portion and having its opening portion cooperatively associated with one of said pole pieces[,] first dynamic convergence coils wound on the respective legs of said first U-shaped core and adapted to be supplied with an electric current of a parabolic waveform; a second U-shaped core provided symmetrically to said first U-shaped core with respect to the axis of said color picture tube and having its opening portion cooperatively associated with the other two pole pieces[,] and second dynamic convergence coils Wound on the respective legs of [each of] said second U-shaped [cores] core[, connected in series with each other] and adapted to be supplied with an electric current of a parabolic waveform[, and a differential coil wound to encircle both of the legs of said second U-shaped core and supplied with an electric current of a parabolic waveform].

2. A dynamic convergence device for a color television receiver as set forth in claim 1, wherein said second dynamic convergence coils are connected in series with each other and a sawtooth wave current produced by a vertical output tube is supplied to one end of the series connection of said second dynamic convergence coils [coil wound on said second core], and pulses provided by a vertical output transformer are applied to the other end of said series connection of said second dynamic convergence [coil] coils.

3. A dynamic convergence device for a color television receiver as set forth in claim 1, wherein [the] said second dynamic convergence [coil] coils [wound on the second U-shaped core] are provided with a center tap, and a variable resistor is connected across the opposite ends of said second dynamic convergence [coil] coils, the movable terminal of said variable resistor being connected with said center tap.

4. A dynamic convergenec device for a color television receiver as set forth in claim 1, wherein fly-back pulses are applied to [the] said differential coil through a polarity changing-over switch.

5. A dynamic convergence device for a color television receiver as set forth in claim 1, wherein said second U-shaped core is further provided with means for adjusting the intensity of magnetization of the two legs of said second U-shaped core.

6. A dynamic convergence device for a color television receiver as set forth in claim 5, wherein said intensity adjusting means is a diflerential coil wound to encircle both of the two legs of said U-shaped core and adapted to be supplied with an electric current of a parabolic waveform.

7. A dynamic convergence device for a color television receiver as set forth in claim 5, wherein said intensity adjusting means is constituted by a circuit connection such that said second dynamic convergence coils are connected in series with each other thereby to supply an electric current into the series connection point of said convergence coils.

References Cited The following references, cited by the Examiner, are of record in the patented file of this patent or the original patent.

UNITED STATES PATENTS 2,672,574 3/1954 Evans 315-13 C 2,855,542 10/1958 Schade 315-13 C 2,875,374 2/1959 Cooper et al. 31513 C 2,903,622 9/1959 Schopp 315-13 0 2,907,915 10/1959 Gleichauf 31513 C MALCOLM F. HUBLER, Primary Examiner US. Cl. X.R. 313-76, 77 

